import { act, render, screen } from "@testing-library/react";
import { describe, expect, it, vi } from "vitest";
import { DRAWIO_EMBED_URL, DrawioView } from "./DrawioView";

/** viewerSays simulates one postMessage frame coming from the iframe. */
function viewerSays(frame: HTMLIFrameElement, payload: unknown) {
	act(() => {
		window.dispatchEvent(
			new MessageEvent("message", {
				data: typeof payload === "string" ? payload : JSON.stringify(payload),
				source: frame.contentWindow,
			}),
		);
	});
}

describe("DrawioView", () => {
	it("points the iframe at the read-only embed viewer", () => {
		render(<DrawioView xml="<mxfile/>" />);
		const frame = screen.getByTitle("draw.io diagram") as HTMLIFrameElement;
		expect(frame.getAttribute("src")).toBe(DRAWIO_EMBED_URL);
		expect(DRAWIO_EMBED_URL).toContain("embed.diagrams.net");
		expect(DRAWIO_EMBED_URL).toContain("proto=json");
		expect(screen.getByText("loading viewer…")).toBeDefined();
	});

	it("answers the viewer's init with a load action carrying the XML", () => {
		render(<DrawioView xml="<mxfile><diagram/></mxfile>" timeoutMs={60000} />);
		const frame = screen.getByTitle("draw.io diagram") as HTMLIFrameElement;
		const target = frame.contentWindow;
		if (!target) {
			throw new Error("jsdom iframe has no contentWindow");
		}
		const posted = vi.spyOn(target, "postMessage");

		viewerSays(frame, "not json");
		expect(posted).not.toHaveBeenCalled();

		viewerSays(frame, { event: "init" });
		expect(posted).toHaveBeenCalledTimes(1);
		expect(JSON.parse(String(posted.mock.calls[0][0]))).toEqual({
			action: "load",
			xml: "<mxfile><diagram/></mxfile>",
			autosave: 0,
		});
		expect(screen.queryByText("loading viewer…")).toBeNull();
		expect(frame.hidden).toBe(false);
	});

	it("ignores messages from other windows", () => {
		render(<DrawioView xml="<mxfile/>" timeoutMs={60000} />);
		act(() => {
			window.dispatchEvent(
				new MessageEvent("message", {
					data: JSON.stringify({ event: "init" }),
					source: window,
				}),
			);
		});
		expect(screen.getByText("loading viewer…")).toBeDefined();
	});

	it("falls back to a notice when the viewer never answers", async () => {
		render(<DrawioView xml="<mxfile/>" timeoutMs={20} />);
		await act(async () => {
			await new Promise((resolve) => setTimeout(resolve, 60));
		});
		expect(screen.getByText(/is not reachable/)).toBeDefined();
		expect(
			(screen.getByTitle("draw.io diagram") as HTMLIFrameElement).hidden,
		).toBe(true);
	});
});